This essay aims to examine the roles of ideas and interests in political economy drawing primarily on theories developed by Karl Marx and Max Weber. The two authors have very different views on the drivers of historical development, the establishment of capitalism and the structure of modern society. Marx's conception of historical materialism emphasizes the role of material interests in constructing the boundaries and structure of the political economy. Max Weber's notion of Protestant ethics emphasizes the role of ideas and norms in shaping rational action and modern society. This essay will explore, compare and discuss these two authors and their views. First, I will give brief definitions of the concepts of interests and ideas. The underlying ontological debates regarding the formation of these concepts will be avoided and the boundaries of the concepts will evolve throughout the essay. Second, I will examine the role of interests in Marx's theories by examining his notion of historical materialism, his structure of society, and Marxist theories of the state. Third, I will compare Marx's theories to Max Weber's notion of rationalization processes, his structure of society, and Protestant ethics. The concept of interest will be defined here as the actual material needs or desires of the main actors, including individuals and individuals. groups in society. (Hall, 1979, p. 176) The concept of ideas will be defined here as a mental representational image of an object. (Audi, 1999, p. 411) Marx and the role of interests Marx begins his notion of historical materialism by distinguishing the existences of humanity from those of animals by the fact that humanity produces its own means of subsistence. This is what he calls......middle of article......ic and the spirit of capitalism London: Routledge ClassicsDas, JR (2006) “Marxist Theories of the State” In : Pressman, S. (2006) Alternative theories of New York State: Palgrave MacmillanHall, PA (1979) "The role of interests, institutions and ideas in the comparative political economy of industrialized nations" In: Lichbach, IM and Zucker-man, A. (1979) Comparative Politics: Rationality, Culture and Structure Cambridge University PressBecker, SO and Woessman L. (2009) “Was Weber Wrong? A theory of human capital from Protestant economic history' The Quarterly Journal of Economics 124(2) pp. 531- 596 Habermas, J (1975) 'Towards a reconstruction of historical materialism' Theory and Society 2(1) pp. 287-300Vanberg, V and Buchanan, JM (1989) “Interests and theories of constitutional choice” Journal of Theoretical Politics 1(1) pp.. 49- 62